Informatics Publishing Limited

K. Kalimuthu ¹, R. Kumar ¹

Affiliations
1 SRM University, Chennai, IN

Abstract

Cognitive radio devices will be able to sense and dynamically use frequency bands for network access. This will be done by autonomous detection of unoccupied bands in the radio spectrum. Several factors like fading and shadowing affects the ability of the cognitive radio to detect the primary user. The current research shows that cooperation among the cognitive users can increase the detection probability for a given probability of false alarm. Previous research work shows that, the probability of detection is achieved maximum of 0.9 in AWGN channel. In this paper, we propose a new method for capacity maximization by minimizing probability of signal outage. And also increases the probability of detection by increasing sensing time for Rayleigh fading channel. Simulation results show promising performance results of the proposed technique are increased probability of detection and considerably maximizing the channel capacity.

Keywords

Cooperative, Energy Detection, Outage Probability and Rayleigh Fading.

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C. T. Manimegalai ¹, Sabitha Gauni ¹, K. Kalimuthu ¹, R. Kumar ¹

Affiliations
1 Telecommunication Engineering Department and ECE, SRM University, Kattankulathur - 603203, Tamil Nadu, IN

Abstract

Ultra Wide Band (UWB) technology is a fast emerging technology for short distance wireless communication. UWB plays a preeminent role in the short range wireless systems, due to the advantages of high speed, low power consumption and very high security. Methods/Statistical Analysis: With cooperative communication as a decisive member in its side this paper proposes cooperative MB-OFDM communication using effective grouped relays in multichannel with use of Dual Carrier Modulation (DCM) for UWB systems. We can attain maximum diversity by using simple Maximum Likelihood (ML) receiver without reduction of data rate as its found using almounti coding which is most used to provide diversity in cooperative communication. Findings: The Proposed method’s resulting diversity is observed using outage probability as a basic parameter and also how the outage probability varies in accordance to threshold power. Application/Improvements: The results shows an improved BER versus SNR with effect of CFO is considered and the improvement in channel capacity and data rate of various different modulation schemes is obtained by varying SNR and distance.

Keywords

Dual Carrier Modulation (DCM), MultiBand Orthogonal Frequency Division Multiplexing (MB-OFDM), Single-Input Multi-Output (SIMO), Multi-Input Multi-Output(MIMO), Ultra Wide Band (UWB)

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C. T. Manimegalai ¹, K. Kalimuthu ¹, Sabitha Gauni ¹, R. Kumar ¹

Affiliations
1 Department of Telecommunication Engineering and ECE, SRM University, Chennai - 603203, Tamil Nadu, IN

Abstract

Background/Objectives: In underlay cognitive radio network, the power control systems play a major role where the secondary users should not affect the primary users transmission. The interference constraints are not attained by all users as the Signal to Interference Noise Ratio (SINR) of the target requirement is not satisfied in the distributed algorithm for power control. Hence, an algorithm is proposed to reduce the power and to regulate the interference constraints of the primary and secondary users. The SINR also has to be maintained. In the proposed method, the distributed statistical algorithm is used when the interference constraints is not available when all transmitters are in active mode to obtain an efficient solution. Methods: In order to minimize the level of SINR for each link between primary and secondary user, a distributed algorithm for power control is proposed. The traditional power control algorithms are used to maintain the secondary users transmission within specific power levels. The main drawback of the traditional algorithms is that the constraints are not met when all the transmitters are active. Result: A Power minimizing algorithm along with the distributed statistical elimination algorithm, to suppress the transmission of selected number of links when all the nodes are active is proposed. This satisfies the SINR requirement of the secondary links. Application: The proposed elimination algorithm enables the optimized power distribution, hence it is a more practical solution in networks with increased number of secondary users.

Keywords

Cognitive Radio Networks (CRN), Distributed Stochastic Algorithms (DSA), Distributed Algorithm for Power Control, Interference Constraints, Power Reduction Algorithm

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Mohammed C. Aejaaz Ahmed ¹, K. Kalimuthu ¹

Affiliations
1 SRM University, Kattankulathur, IN

Abstract

In the recent times, usage of mobile devices has been increased many fold. So, this is very serious problem in wireless communications. This leads to inaccessibility to the mobile services. If this is the situation in today's scenario then in future it would be more hard to provide valid access to all the users simultaneously. Cognitive Radio is a future technology to provide worldwide roaming to improve connectivity and also to have worldwide roaming and interoperability the "cognitive radio" concept was coined. In this proposed paper, a scheme including power allocation scheme and a prioritization scheme is used to achieve higher capacity with the same power. This is done by utilizing a simulated cognitive radio scenario.

Keywords

Cognitive Radio, MIMO-OFDM, Capacity Maximization, Prioritization, Power Allocation.

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